1. Technical Field
The present invention relates to an illumination device and a projector.
2. Related Art
In recent years, an illumination device using a light-emitting element, such as a semiconductor laser from which high-luminance, high-output light is obtained, has attracted attention as an illumination device used for a projector. In the illumination device, a predetermined region of a phosphor layer is uniformly illuminated by light from a plurality of light-emitting elements with the use of a pair of multi-lens arrays (e.g., see JP-A-2014-138148).
For emitting laser light onto the predetermined region of the phosphor layer, each of a plurality of beams emitted from the multi-lens array in the front stage has to be incident on the corresponding lens of the multi-lens array in the rear stage. However, some deviation (mounting error) unavoidably occurs in the alignment of an optical system or light-emitting element that is located in the front stage of the front-stage multi-lens array. The “mounting error” herein includes a deviation in alignment due to tolerances of an optical system such as the front-stage multi-lens array or the light-emitting element.
If such a mounting error is present, the beam emitted from the front-stage multi-lens array cannot be incident on the corresponding lens of the rear-stage multi-lens array. The beam is emitted onto a region other than the predetermined region, resulting in the problem of a reduction in light-use efficiency.